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Swimming exercise and race performance in Thoroughbred racehorses

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Abstract

Swimming has become an accepted part of the training programme of race horses. The purpose of this study was to establish whether it was possible to perform a standardized swimming test in race horses and to evaluate whether exercise variables calculated from this test were related to race track performance. Fifty-two Thoroughbred racehorses (4.6±1.4 years; 50 geldings and 2 stallions) participating in races at the Hong Kong Jockey Club (HKJC), were used in the study. All horses underwent a swimming test consisting of two laps of an oval shaped swimming pool (1 lap=±60m). During the swimming test, heart rate (HR; beats/min) and speed (V; m/s) of the horses were monitored. Additionally, 10 of the 52 horses were tested a second time (after 1–21 days), to evaluate the repeatability of the swimming test and after the second swimming test plasma lactate concentration (LA; mmol/L) was estimated. ‘Performance Rating’ of horses was defined by the rating score determined by the HKJC, based upon race performance. For a second performance parameter (‘Performance Category’), horses were divided into ‘good performers’ (placed in 1 to 5 rank at competition in the period between 1 month before to 1 month after the swimming test) and ‘average performers’ (placed at lower rankings). Mean HR during the first swimming test was 178±14bpm, the mean V was 1.06±0.10m/s. There was a significant correlation between HR and V (r=0.720, P<0.001, n=52), but HR was not repeatable between tests (r=0.390, P=0.265, n=10). No significant correlation was found between racing performance and heart rate, speed or plasma lactate concentration. Under the existing circumstances it was not possible to perform a repeatable standardised swimming test. The results of the swimming test were not a useful predictor of either Performance Rating or Performance Category. Some horses reached high heart rates during the swimming test and one horse also showed a plasma lactate concentration above anaerobic threshold, indicating that the exercise of swimming may not be always as mild as some trainers think.
Pferdeheilkunde 30 (2014) 403
Pferdeheilkunde 30 (2014) 4 (Juli/August) 403-406
Swimming exercise and race performance
in Thoroughbred racehorses
Mariet Klomp1, Carolien C. B. M. Munsters1,2, Marianne M. Sloet van Oldruitenborgh-Oosterbaan1
1Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
2Moxie Sport Analysis & Coaching, Uden, the Netherlands
Abstract: Swimming has become an accepted part of the training programme of race horses. The purpose of this study was to establish
whether it was possible to perform a standardized swimming test in race horses and to evaluate whether exercise variables calculated from
this test were related to race track performance. Fifty-two Thoroughbred racehorses (4.6±1.4 years; 50 geldings and 2 stallions) partici-
pating in races at the Hong Kong Jockey Club (HKJC), were used in the study. All horses underwent a swimming test consisting of two laps
of an oval shaped swimming pool (1 lap = ±60 m). During the swimming test, heart rate (HR; beats/min) and speed (V; m/s) of the horses
were monitored. Additionally, 10 of the 52 horses were tested a second time (after 1–21 days), to evaluate the repeatability of the swim-
ming test and after the second swimming test plasma lactate concentration (LA; mmol/L) was estimated. ‘Performance Rating’ of horses
was defined by the rating score determined by the HKJC, based upon race performance. For a second performance parameter (‘Perfor-
mance Category’), horses were divided into ‘good performers’ (placed in 1 to 5 rank at competition in the period between 1 month before
to 1 month after the swimming test) and ‘average performers’ (placed at lower rankings). Mean HR during the first swimming test was
178±14 bpm, the mean V was 1.06± 0.10m/s. There was a significant correlation between HR and V (r=0.720, P< 0.001, n = 52), but
HR was not repeatable between tests (r=0.390, P=0.265, n=10). No significant correlation was found between racing performance and
heart rate, speed or plasma lactate concentration. Under the existing circumstances it was not possible to perform a repeatable standar-
dised swimming test. The results of the swimming test were not a useful predictor of either Performance Rating or Performance Category.
Some horses reached high heart rates during the swimming test and one horse also showed a plasma lactate concentration above anaer-
obic threshold, indicating that the exercise of swimming may not be always as mild as some trainers think.
Keywords: swimming test / performance / heart rate / speed / Thoroughbred racehorse / exercise physiology
Schwimmtraining und Rennleistung beim Vollblut-Rennpferd
Schwimmen hat sich zur anerkannten Trainingsmethode für Rennpferde entwickelt. Ziel dieser Studie was es festzustellen, ob es beim Renn-
pferd möglich ist, einen standardisierten Schwimmtest durchzuführen und zu prüfen, ob die Leistungsvariablen aus diesem Test zu der Renn-
leistung auf der Bahn in Beziehung gesetzt werden können. 52 Rennpferde (4.6 ±1.4 Jahre; 50 Wallache und 2 Hengste), die im Hong-
kong Jockey Club (HKJC) im Rennen standen, nahmen an der Studie teil. Alle Pferde wurden einem Schwimmtest unterzogen, der in zwei
Runden in einem ovalen Pool (1 Runde= 60 m) bestand. Während des Tests wurden Herzfrequenz (HR, bpm) und Geschwindigkeit (V, m/s)
der Pferde aufgezeichnet. Zusätzlich wurden 10 der 52 Pferde nach 1–21 Tagen ein zweites Mal getestet, um die Wiederholbarkeit des
Test zu überprüfen. Nach diesem zweiten Test wurd auch die Plasmalaktatkonzentration (LA, mmol/L) gemessen. Die Leistungsbeurteilung
der Pferde wurde anhand des Scores definiert, der vom HKJC basierend auf der Rennleistung festgelegt worden war. Für einen zweiten Lei-
stungsparameter (Leistungskategorie) wurden die Pferde in „gute Leistungsbringer“ (1.-5. Platzierung im Zeitraum von 1 Monat vor bis 1
Monat nach dem Schwimmtest) und „durchschnittliche Leistungsbringer“ (nachrangige Platzierungen) eingeteilt. Die mittlere Herzfrequenz
während des Schwimmtests war 178±14 bpm, die mittlere Geschwindigkeit V war 1,06 ± 0,10 m/s. Zwischen HR und V bestand eine sig-
nifikante Korrelation (r= 0,720, P< 0,001, n= 52), jedoch war HR zwischen den verschiedenen Test nicht wiederholbar (r = 0,390,
P= 0,265, n =10). Zwischen Rennleistung, HR, V und Plasmalaktatkonzentration bestand keine signifikante Korrelation. Unter den gege-
benen Umständen war es nicht möglich, einen wiederholbaren standardisierten Schwimmtest durchzuführen. Die Testergebnisse ließen kei-
ne brauchbare Vorhersage weder für die Leistungseinschätzung noch für die Leistungskategorie zu. Einige Pferde erreichten während des
Tests hohe Herzfrequenzen und ein Pferd zeigte zudem über der anaeroben Schwelle liegende Plasmalaktatkonzentration, was darauf hin-
weist, dass Schwimmtraining nicht immer so „sanft“ ist, wie manche Trainer meinen.
Schlüsselwörter: Schwimmtest / Leistung / Herzfrequenz / Geschwindigkeit / Vollblutrennpferd / Leistungsphysiologie
Correspondence: Prof. Dr. Marianne Sloet, Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht,
Yalelaan 112, 3584 CM Utrecht, The Netherlands, Email: m.sloet@uu.nl
Citation:
Klomp M., Munsters C. C. B. M1, Sloet van Oldruitenborgh-Oosterbaan M. M. (2014)
Swimming exercise and race per-
formance in Thoroughbred racehorses. Pferdeheilkunde 30, 403-406
Swimming exercise and race performance
M. Klomp et al.
Introduction
In some racing stables, swimming has become an accepted
component of the training programme of race horses. Swim-
ming is considered to be a relatively safe exercise for a horse
because it is thought to provide sufficient workload with only
limited strain on the limbs (
Thomas
et al. 1980,
Misumi
et al.
1994a).
Although no specific research on the possible correlation bet-
ween swimming and track performance of race horses has
been reported, the same linear increase in HR with increasing
workload for horses running on the track has been found for
swimming horses (
Thomas
et al. 1980). More experienced
horses have been shown to have a lower HR after swimming
than those that were less experienced in their training regimen
403-406_Klomp.qxp_Musterseite Artikel.qxd 13.05.14 13:11 Seite 403
(
Garcia
and
Beech
1986). In swimming horses a positive cor-
relation between maximum heart rate and swimming speed
has also been shown, but there was no significant difference
between the start and the end of a training period (
Misumi
et
al. 1994b). This may be due to the fact that the horses in this
study were not sufficiently accustomed to swimming and stress
may have influenced the HR of horses during swimming tests
(
Misumi
et al. 1994b).
During the racing season, the results of individual racehorses
are closely monitored by the trainer. For horses that get regu-
lar swimming exercise and are accustomed to it, the measu-
rement of exercise variables during swimming would be use-
ful as a predictor of racing performance. The aim of the pre-
sent study was to investigate whether heart rate and speed
obtained during a standardized swimming test in racehorses
that get regular swimming exercise, could be used to evaluate
or predict on-track performance.
Materials and methods
Horses
In this study 52 Thoroughbred racehorses (mean age
4.7±1.4 years, 50 geldings and 2 colts) were used. All hor-
ses were housed in individual stalls in eight different trainer
departments at the Hong Kong Jockey Club (HKJC), and their
housing, feeding and training was managed by their trainers
(on average seven horses per trainer). All horses were trained
six days a week in the swimming pool and on the track accor-
ding to the training regimen of the trainer, and the seventh
day was a rest day.
Set up
All 52 horses were tested in a standardized swimming test.
Ten out of the 52 horses were tested twice to assess the repe-
atability of the results, with an interval of 1–21 days between
test, depending on availability of the horse between the two
swimming tests (test-1 and test-2). In these 10 horses a jugu-
lar blood sample was taken after the test to determine plasma
lactate concentration after swimming.
The swimming pool at the HKJC is an oval shaped pool with
22 meter straights and separate entrance and exit (Figures 1
and 2). The water in the pool was 2.6 m deep; horses there-
fore have no contact with the ground while swimming. During
swimming the horses were guided by their own handler, along
the outer edge of the pool. The water in the pool was not
heated and the mean outside temperature was around 25°C
during the whole experimental period.
Swimming test protocol and blood sampling
All 52 horses were tested using the same protocol. The heart
rate monitoring equipment was fitted in the stable and the
horse was hand-walked to the swimming pool. The test con-
sisted of two laps of the pool. In the pool horses could take
the inside or the outside of each corner, so to standardise
distance versus HR only the 22 meter long straights of the
Swimming exercise and race performance
M. Klomp et al.
Pferdeheilkunde 30 (2014)
404
pool were used to calculate mean HR and mean V. The first
straight was not used in the data collection to allow the hor-
ses to adjust to the exercise. The data collected during swim-
ming included the mean HR and V for the second, third and
fourth straight of the pool. In a subgroup of ten horses, a sin-
gle heparinised blood sample was taken 1 minute after com-
pleting the swimming test and this was cooled immediately.
Plasma lactate concentration was measured using a portable
instrument (Lactate Pro™)within 15 minutes after collection.
The device has been shown to be accurate in equine blood
assay (
Sloet
et al. 2008).
Heart rate measurements
The heart rate (HR) during swimming was measured using a
HR monitor (Polar RS400, Polar Electro Oy, Kempele, Fin-
land) with two plastic transmitters containing the electrodes.
The two electrodes were placed on wet skin under the girth
behind the left elbow and behind the left withers. The electro-
des were held in place by an elastic strap and a small racing
breastplate. HR monitors continuously recorded heart rate
(HR; beats/min) each second during the swimming test. The
time was recorded for each straight using a stopwatch and
the mean HR and mean V(m/s) were then calculated.
Fig. 1 Schematic representation of the swimming pool for horses
at the Hong Kong Jockey Club: The pool is oval shaped with a sepa-
rate entrance and exit; horses are guided in and out by a steep ramp
which is covered with rubber tiles; in the middle of the pool is an
island, so horses are forced to swim the full oval.
Fig. 2 Swimming pool for horses at the Hock Kong Jockey Club;
horses always swim the full oval (the short-cut in the middle was not
used).
403-406_Klomp.qxp_Musterseite Artikel.qxd 13.05.14 13:11 Seite 404
Evaluation of racing performance
‘Performance Rating’ around the swim date was obtained for
each horse using the HKJC rating. This is a cumulative rating
which is based on the outcome of all race competitions
during the racing career up to the swim date for each horse.
In addition, horses were classified as ‘good performers’ if they
were placed in the top 5 in a race or as ‘average performers’
if they finished lower than fifth place (
Couroucé
et al. 1997).
Races in the period from 1 month prior to 1 month after swim
date were evaluated to determine this ‘Performance Catego-
ry’.
Data analysis
Data from all horses were used to calculate the correlation
between HR and speed, using a Pearsons product-moment
correlation. For the relationship between HR, speed, rating
and performance a linear model was used, residues were
checked for normality with QQ-plots. In the subgroup of ten
horses the correlations between HR and speed, HR and LA
and speed and LA were calculated using a Pearson’s product-
moment correlation. The relationships between LA, rating and
performance were also analysed using a linear model and
residues were checked for normality with QQ-plots.
Results
All horses
HR values of all horses in the first test ranged from 130 to
202 bpm with an average of 178±14 beats/min. Swimming
speed ranged from 0.79 to 1.28 m/s with an average of
1.06± 0.09 m/s. The heart rate of the horses was significant-
ly correlated with swimming speed (r= 0.720, P < 0.001)
(Figure 3). Performance Rating and Performance Category
were not correlated to HR or swimming speed.
Horses tested twice
In this subgroup of horses (n=10), HR values ranged in test-
1 from 163 to 193 beats per minute with an average of
176±10 beats/min and in test-2 from 149 to 209 beats/min
with an average of 179±16 beats/min (Figure 4). HR was
not significantly correlated between test-1 and test-2
(r= 0.390, p = 0.265).
Swimming exercise and race performance
M. Klomp et al.
Pferdeheilkunde 30 (2014) 405
Mean swimming speed of test-1 was 1.05±0.073 m/s (ran-
ge 0.98 to 1.23m/s) and of test-2 1.06± 0.08 m/s (range
0.96–1.20 m/s). Speed was significantly correlated between
test-1 and test-2 (r= 0.670; p= 0.034).
The average plasma lactate concentration in the subgroup
was 2.3±1.6mmol/L. No significant correlation was found
between mean heart rate or mean speed and plasma lactate
concentration LA. Performance Rating and Performance
Category showed no correlation with the plasma lactate con-
centration. A single horse had a higher than average plasma
lactate concentration of 6.6mmol/L.
Discussion
The heart rate values of 130–202 bpm obtained during the
swimming tests were closely comparable with the 130–210
bpm previously reported (
Hobo
et al. 1998,
Misumi
et
al.1994a and b,
Thomas
et al. 1980). Maximum heart rate
during the swimming test in the present study (202 bpm) was
lower than the average maximum heart rate of 223 bpm in
Thoroughbred horses during a race (
Krzywanek
et al. 1970).
In the present study, it was found that heart rate during the
swimming test was not a good predictor of performance on
the race track. Other previous studies on swimming test and
race performance were also unable to establish a correlation
(
Misumi
et al. 1994a, b). Therefore, it seems that there is no
relationship between the heart rate of horses during a swim-
ming test and race track performance.
In the present study heart rate of horses was not repeatable
between two swimming tests. However,
Garcia
et al. (1986)
found that heart rate of horses between two repeated swim-
ming tests were comparable (117± 8 bpm and 110 ± 5
bpm). The reason for the lack of repeatability of heart rate in
the present study is not clear, but it may be partly explained
by the variable period between the repetition of the two tests.
Other possible explanations may be that the intensity of the
swimming test used in the study of
Garcia
et al. (1986) was
lower than the average intensity during the swimming test in
the present study (130–202 bpm) and therefore the heart
Fig. 4 Correlation between mean heart rate and mean speed in
the subgroup of 10 horses that were tested twice in a swimming
pool.
Fig. 3 Correlation between mean heart rate and mean swim-
ming speed in 52 horses performing a swimming test.
403-406_Klomp.qxp_Musterseite Artikel.qxd 13.05.14 13:11 Seite 405
rate variations smaller. Finally, the sample size might have
been too small in the present study.
The swimming speed of horses was significantly correlated
between the two swimming tests. Each horse appeared to
swim at its own ‘preferred’ swimming speed, and from the
authors experience it proved very difficult to change a horses’
speed during swimming. There was also no relationship bet-
ween swimming speed and Performance Rating or Performan-
ce Category.
The average plasma lactate concentration (2.3±1.6 mmol/L)
obtained in this study is comparable with data found in earlier
swimming studies (
Hobo
et al. 1998,
Gatta
et al. 1999). In
the present study one horse had a higher plasma lactate con-
centration after the swimming test (6.6mmol/L); this suggests
that during swimming exercise the anaerobic contribution to
the energy demands of this horse was quite significant. The-
refore, it might be important for horse trainers to appreciate
that swimming should not be considered as a mild exercise
for every individual horse – a conclusion that has also been
suggested by other authors (
Thomas
et al. 1980).
A correlation between plasma lactate concentration and
racing performance of Thoroughbred race horses was
demonstrated during a standardised treadmill test (
Evans
et
al. 1993), but in the present study, LA during the swimming
test was not correlated to Performance Rating or Performance
Category.
Misumi
(1994a,b,c) found no differences in LA bet-
ween a swimming test at the beginning of a training period
and after four months of training. Therefore, it also seems
likely that there is no correlation between plasma lactate con-
centrations during a swimming test and the performance of
race horses.
Conclusions
In the present study it was not possibe to standardise a swim-
ming test in race horses. Mean heart rate, mean speed and
plasma lactate concentrations during a swimming test were
not useful indices of the racing performance. In some horses
swimming exercise may not be such ‘mild’ exercise as is
sometimes suggested.
Swimming exercise and race performance
M. Klomp et al.
Pferdeheilkunde 30 (2014)
406
Acknowledgements
The authors thank dr. Greg O. Sommerville for the opportu-
nity to perform this study at the Hong Kong Jockey club and
for all his advice and help during the study. We are also very
grateful to all trainers and owners of the horses that partici-
pated in the study. We thank dr. Jan van den Broek for stati-
stical evaluation.
References
Couroucé A., Chatard J. C., Auvinet B.
(1997). Estimation of perfor-
mance potential of Standardbred trotters from blood lactate con-
centrations measured in field. Equine Vet. J. 29, 365-369
Evans D. L., Harris R. C., Snow D. H
. (1993) Correlation of racing
performance with blood lactate and heart rate after exercise in
Thoroughbred horses. Equine Vet. J. 25, 441-445
Garcia M. C., Beech J.
(1986) Endocrinologic, hematologic, and
heart rate changes in swimming horses. Am. J. Vet. Res. 47, 2004-
2006
Gatta D., Casini L., Magni L., Colombani B.
(1999) The workload
during swimming training in Thoroughbreds: comparison with two
different training sessions on the track. Annali della Facolta di
Medicina Veterinaria di Pisa 52, 179-187
Hobo S., Yoshida K., Yoshihara T.
(1998) Characteristics of respira-
tory function during swimming exercise in Thoroughbreds. J. Vet.
Med. Sci. 60, 687-689
Krzywanek H., Wittke G., Bayer A., Borman P.
(1970) The heart rates
of Thoroughbred horses during a race. Equine Vet. J. 2, 115-117
Misumi K., Sakamoto H., Shimizu R.
(1994a) The validity of swim-
ming training for two-year-old Thoroughbreds. J. Vet. Med. Sci.
56, 217-222
Misumi K., Sakamoto H., Shimizu R
. (1994b) Changes in blood lac-
tate and heart rate in Thoroughbred horses during swimming and
running according to their stage of training. Vet. Rec. 135, 226-
228
Misumi K., Hirakawa A., Sakamoto H., Shimizu R.
(1994c). Principal
component analysis, using the measurements during running and
swimming test in Thoroughbred horses. J. Vet. Med. Sci. 56,
1075-1080
Sloet van Oldruitenborgh-Oosterbaan M. M., van den Broek E. T.
W., Spierenburg A. J.
(2008) Evaluation of the usefulness of the
portable device Lactate Pro for measurement of lactate concentra-
tions in equine whole blood. Vet. Diagn. Invest. 20, 83-85
Thomas D. P., Fregin G. F., Gerber N. H., Ailes N. B
. (1980). Car-
diorespiratory adjustments to tethered-swimming in the horse.
Pflügers Archiv: Europ. J. Physiol. 385, 65-70
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The purpose of this study was to examine the relationship between V4 (velocity which results in a blood lactate concentration of 4 mmol/1), age and racing performance of Standardbred trotters and to establish V4 normal values to select good and poor performers. The specific influence of racing (RT) and training (T1 and T2) tracks was also examined. A total of 159 horses were divided into 5 age-groups from 2 to 6 and over and performed 330 standardised exercise tests of 3 steps performed at increasing speeds. The velocity of the horses was measured with a tachometer on the sulky. Blood lactate concentrations were measured from the jugular vein after each step. For the 5 age-groups, mean V4 values increased significantly (P<0.05) with age between 2 and 4 years. After 5 years, this increase was reduced and became nonsignificant. The highest V4 values were obtained on the racing track (RT) and the lowest on the training tracks (T1; P<0.05). No significant difference was found between RT and T2 nor between T1 and T2. Horses were defined as good performers (GP) when finishing between the first and the fifth place in a race or poor performers (PP) when finishing lower than fifth. V4 was significantly higher for GP than for PP (P<0.05). Normal value of V4 were established for good and poor performers taking into account the 95% confidence interval of the data. Therefore, V4 depends on age and track and can be considered an important parameter to evaluate trotters' racing potential.
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Two identical experiments, using Standardbred and Thoroughbred horses (experiment A, n = 31; experiment B, n = 17) on a swimming regimen, were performed 1 week apart to evaluate short-term heart rate, hematologic, and endocrinologic changes. Horses were placed in 4 categories based on duration of swimming (1 to 5, greater than 5 to 10, greater than 10 to 15, and greater than 15 minutes). Heart rate, PCV, and plasma concentrations of total protein, cortisol triiodothyronine, thyroxine, insulin, and glucose of each horse were evaluated before, immediately after, and 1 hour after swimming. For experiment A, there was a main effect of time of sampling on PCV, total protein, triiodothyronine, thyroxine, and insulin. There was a main effect of duration of swimming on insulin concentration and an interaction of duration of swimming and time of blood collection on heart rate and cortisol concentration. For experiment B, there was a main effect of time of blood collection on all the variables except glucose.
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The cardiorespiratory and metabolic responses to various levels of tethered-swimming were evaluated in 5 sedentary horses. Cardiac output (Q) and heart rate (HR) correlated highly (r = 0.89 and 0.94 respectively) with work effort (WE) expressed as kg pulled . kg body wt-1 . 10-2. While swimming, stroke volume (SV) was reduced at the lowest workloads, but increased with increasing WE so that at the highest workloads it had returned to the on-land standing SV. Pressures in the pulmonic as well as on both sides of the systemic circulation were considerably elevated by this form of exercise, although only mean carotid artery pressure (CAP) correlated highly (r = 0.83) with WE. During tethered-swimming plasma lactic acid (LA) rose exponentially from 1 to 10 mmol . 1-1 with increasing HR over the range 150-200 beats . min-1. Oxygen uptake (VO2) increased linearly (r = 0.95) from 25-112 ml . kg-1. min-1 over the We range of 3.0-7.8 kg pulled . kg body wt-1. 10-2. The aerobic capacity of the equine species would appear to be twice that of man. The greater increase in VO2 in the exercising horse cannot be explained solely on the basis of increases in Q. Therefore alterations in hematocrit, hemoglobin and oxygen extraction appear to play a more important role in the horse during exercise than they do in man.
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To investigate whether the running exercise fitness of individual horses could be assessed by a standardized swimming exercise test, the results of multivariate analysis of the exercise parameters measured during incremental running and swimming tests were compared. Ten thoroughbred horses were subjected to different types of exercise tests on a track or in a pool, and the maximum heart rate during and the blood lactate concentration immediately after the exercise were examined. Serial exercise parameters (VLA2, VLA4, LA0, V150, V200, HRS, HRLA2, HRLA4) referred to as the indices related to the adaptation of cardiovascular or metabolic systems were computed using the relationships between these measurements and velocity during each test, and were analyzed by a multivariate procedure, i.e. the principal component analysis. The correlation diagram between the exercise parameters on the first two component axes in running were similar to that in swimming. When the exercise fitness in each horse was compared between running and swimming, three horses trained by short-term endurance exercise were statistically distinguished in both tests and differed as a group from the other horses. Therefore, it is thought that evaluation of the exercise fitness in swimming using the multivariate analysis is useful for predicting poor performing horses on a track.
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The purpose of this study was to investigate whether the change in the performance capacity of horses trained by running could be evaluated with a standardised swimming exercise test as well as by a standardised running exercise test. Seven two-year-old thoroughbred horses were trained by running for four months and were subjected to a standardised swimming exercise tolerance test before the training began and after two and four months of training in addition to the standardised running tolerance test after two and four months of training. The running training brought about a significant change in the correlation between the swimming speed of the horses and their blood lactate concentration, and the correlation between the blood lactate concentration and maximum heart rate and running speed also changed significantly after two months of training.
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To investigate the validity of swimming training, the following matters were considered: 1) changes in the performance capacity, 2) changes in the constitution and 3) frequency of locomotor diseases. These were evaluated during a training program including both conventional exercise on a track and swimming. In this study, 24 two-year-old thoroughbred horses were studied, and divided into the following three groups: Group A, trained by only running; Group B, trained by running plus a gradual increase in swimming; Group C, trained by running plus constant swimming. As a result of standardized exercise tests, only the intercepts of the 3 regression curves between the speed and the blood lactate concentration in Group B increased significantly as the training progressed. While the growth in height in Groups B and C were greater than in Group A, the increase in girth and weight in Groups B and C were smaller than in Group A. The percentages with locomotor diseases during this experiment in Groups A, B, and C were 62.5%, 12.5% and 25.0%, respectively, and there was a significant difference (p < 0.05) between Group A and Group B. As mentioned, it was suggested that a training program including swimming training is seen as being useful for improvement in performance capacity, since it can reduce locomotor diseases in young horses and allow for smooth progress in future training.
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Equine respiratory patterns during swimming were examined in five normal horses. The experiment included a preliminary warming-up stage and 6 circuits of swimming around an annular pool of a 50-meter-circumference. The horses were examined for respiratory rates, intratracheal pressures, inspiratory time (TI), expiratory time (TE), respiratory cycle (T; TI + TE), heart rates, blood lactate concentrations, hematocrit and blood gases. The respiratory rates were maintained around 25/min. Blood gas values changed significantly during swimming. The intratracheal pressures during expiration and inspiration increased significantly with exercise duration compared to the immediately after the warming-up stage. The duty ratio (TI/T) averaged 0.33, which implied that the expiratory time was roughly doubled the inspiratory time. We considered that a longer expiratory time may limit sudden collapse of airways by water pressure during swimming and prevent a radical decrease of air space volume, thus maintains buoyancy.